It is over half a century since a young Thomas Keneally had a breakdown and abandoned his studies at an Australian seminary. His Catholicism, he now says, is more cultural than practising, yet he still knows better than most the mindset of today’s priests.

Crimes of the Father, a characteristically brave and unflinching novel by the Booker and Miles Franklin prize-winner, examines how the overwhelming majority of Catholic clerics, who may struggle with their vow of celibacy but still manage to give something positive to the world, are coping in an institution where a tiny minority have abused children, too often while the church turns a blind eye.

Psychologist and monk Father Frank Docherty is, his younger brother says (and no doubt speaking for the author), “the real bloody deal” as far as priests go. Exiled by his home cardinal in Sydney as a young priest in the 1970s, on account of his radicalism, opposition to apartheid and the Vietnam war, he returns 25 years later to visit his feisty but ailing mother. He has been living an academic life in Canada, researching the tidal wave of revelations about paedophile priests that have so drained Catholicism’s moral authority.

On home leave, with family matters uppermost in his mind, he nevertheless stumbles across allegations of abuse against a senior monsignor in the local archdiocese, who also happens to be the brother of the woman who, many years previously, had brought Docherty to the point of leaving the priesthood.

Unlike the church authorities, when confronted with the facts Docherty doesn’t look away, or ignore the pain of the bereaved and broken mother of a young victim who has killed himself. And so, with a prophetic moral clarity, he challenges the bullying local cardinal, who proffers empty words and hides behind lawyers’ instructions and confidentiality agreements.

Keneally’s theme is sadly familiar, but in the hands of a world-renowned writer – still, on this evidence, at the height of his powers, and with a long record of shining a light on human frailty and injustice – Crimes of the Father goes way beyond the familiar.

It questions what makes a good priest and, therefore, what makes a bad one. And that, Keneally concludes, isn’t only to do with individual make-up, circumstances or choices, but also down to institutional Catholicism and “emotional dwarfism” (the title of one of Docherty’s academic papers).

The charge is often made that the clerical abuse scandal is the consequence of priestly celibacy, but it is too easy an accusation for the Vatican to bat away. Vicars, TV presenters, teachers and many others who are ostensibly “happily married” also commit similarly horrific crimes, it points out. And so, within the church, there remains a resistance to lifting the veil on the real but often indirect damage done to its priests and nuns by a celibate lifestyle embraced and flaunted as a higher calling for the past 1,000 years.

The real question, Keneally suggests, is whether a whole belief system that relies on a rejection of something as essential as sexuality has any role in causing the current crisis. Unless this is addressed honestly – and there is no sign of it happening yet – the church will continue, Docherty tells one of the victims he is consoling, to abuse and hence negate the God-given mandate it claims as its very reason to exist.

• Crimes of the Father by Thomas Keneally is published by Sceptre (£18.99). To order a copy for £16.14 go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99